Method and apparatus for integrating optical fibers with collimating lenses

ABSTRACT

A two-dimensional optical switch ( 10 ) includes a hermetically sealed housing ( 41 ) cooperable with several input fibers ( 11-18 ) and several output fibers ( 21-28 ). A digital micromirror device ( 71 ) is disposed within the housing, and can selectively effect travel of radiation between each input fiber and any one of the output fibers. The housing includes two lens sections ( 56, 57 ), which each have a platelike support portion ( 106 ), and several lens portions ( 111-118 ) of approximately semi-spherical shape that project from the inner side of the support portion. Each of the input fibers is fixedly secured to an outer side of one lens section in alignment with a respective lens portion thereon, and each of the output fibers is fixedly secured to the outside of the other lens section in alignment with a respective lens portion thereon.

TECHNICAL FIELD OF THE INVENTION

This invention relates in general to the handling of optical signalsand, more particularly, to configurations in which several opticalfibers are associated with respective collimating lenses.

BACKGROUND OF THE INVENTION

Telecommunications is a field which has been rapidly evolving over thepast twenty years, fueled in part by the progressively increasingpopularity of technologies such as cellular telephones, facsimilemachines, and computer communications that use the Internet. Due tothese growing new technologies, there has been a progressivelyincreasing demand for telecommunications equipment with greaterinformation-carrying capacity, which in turn has created a progressivelyincreasing focus on effecting communications through the use of opticalsignals.

High bandwidth fiber optic telecommunication systems are being deployedaround the world. This is creating a backbone system which couples majormetropolitan areas. Currently, when these existing systems need toeffect switching of an optical signal, they typically convert theoptical signal into an electrical signal, effect electrical switching ofthe electrical signal, and then convert the resulting electrical signalback into an optical signal. This greatly delays the propagation ofinformation through the system, and is expensive because it increasesthe complexity of the system.

In order to avoid this problem, attempts are being made to developoptical switches which would directly switch optical signals, withouttemporarily converting them into electrical signals. While existingapproaches to optical switching have been generally satisfactory fortheir intended purposes, they have not been satisfactory in allrespects.

For one example, one existing type of optical switch is known as atwo-dimensional optical cross connect (OXC) switch. It has ahermetically sealed housing that contains a digital micromirror device(DMD), which is also sometimes referred to as a micro-electro-mechanicalsystem (MEMS) device. The DMD has a plurality of movable mirror partsarranged in a two-dimensional array. The hermetically sealed housingincludes two transmissive windows arranged at an angle to each other.Externally of the housing, two plates each have several V-shaped groovesthat are formed by diamond point turning and that extend perpendicularto a respective one of the windows. Each groove has a collimating lensmounted therein at a location spaced from the associated window, and hasan optical fiber end mounted therein, often at a location spaced fromthe collimating lens. Radiation traveling through one of the opticalfibers can exit the end of that fiber, pass through the associatedcollimating lens, pass through the associated window, undergo reflectionby a respective mirror part of the DMD, pass through the other window,pass through another collimating lens, and then enter another opticalfiber.

In this type of device, insertion losses from an input fiber to anoutput fiber are relatively high, and are typically on the order of 3 dBto 4 dB. This is due in part to the fact that various individualcomponents have sufficient differences in their coefficients of thermalexpansion so as to generate significant alignment errors across theoperational temperature range of the switch. Further, even for a giventemperature, it is complex and time-consuming to attempt to achievesuitable alignment of the multiple independent components duringassembly of the switch, as a result of which these existing switches arerelatively expensive to make, and the production yields are relativelylow. Also, even though the windows theoretically have no optical power,in practice they are non-ideal and may each have a slight wedge shapethat introduces a small optical power.

A further consideration is that environmental conditions such asvibration and shock can produce dynamic alignment problems between themultiple components. Still another consideration is that there are anumber of optical surfaces that are susceptible to environment factorssuch as dust, moisture and outgassing of plastic or adhesive materialsused to couple the various components together. These optical surfacestypically include the end surface of each fiber, two end surfaces ofeach collimating lens, and the outer surface of each transmissivewindow.

SUMMARY OF THE INVENTION

From the foregoing, it may be appreciated that a need has arisen for amethod and an apparatus that reduce susceptibility to insertion lossand/or environmental factors in a context wherein optical fibers areassociated with respective lens structures. According to one form of thepresent invention, a method and apparatus are provided to address thisneed, and involve: supporting a plurality of optical parts on a base;adjusting a lens section to a selected position with respect to thebase, the lens section including a support portion made of an opticallytransmissive material, and including a plurality of lens portions madeof an optically transmissive material and provided at spaced locationson a first side of the support portion, the lens portions each beingaligned with a respective optical part in the selected position of thelens section; fixedly securing the lens section in the selected positionwith respect to the base; positioning an end of each of a plurality ofoptical fibers to be adjacent the support portion on a second sidethereof opposite from the first side, and to be in an alignment positionwith respect to a respective lens portion; and fixedly attaching the endof each fiber to the second side of the support portion.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present invention will be realized fromthe detailed description which follows, taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a diagrammatic sectional top view of a two-dimensional opticalcross connect switch that embodies the present invention;

FIG. 2 is a diagrammatic sectional side view of the switch of FIG. 1,taken along the line 2—2 in FIG. 1, and which also diagrammaticallyshows in broken lines a fiber positioner and a laser; and

FIG. 3 is an elevational view of an inner side of a lens section whichis a component of the switch of FIG. 1.

DETAILED DESCRIPTION

FIG. 1 is a diagrammatic sectional top view of a two-dimensional opticalswitch 10, which embodies aspects of the present invention. FIG. 2 is adiagrammatic sectional side view of the switch 10, which is taken alongthe line 2—2 in FIG. 1, and which also shows a fiber positioner and alaser that are discussed later.

The optical switch 10 includes eight optical fibers 11-18 that serve asinput fibers, and eight optical fibers 21-28 that serve as outputfibers. Each of the fibers 11-18 and 21-28 is a component of a typeknown to those skilled in the art, and has a central core which isconcentrically surrounded by a cladding. As a matter of convenience forpurposes of explaining the present invention, the fibers 11-18 arereferred to herein as input fibers, and the fibers 21-28 are referredherein as output fibers. However, any of the fibers 21-28 could functionas an input fiber, and any of the fibers 11-18 could function as anoutput fiber. In fact, the switch 10 and the fibers 11-18 and 21-28 arebidirectional, and fully capable of handling simultaneous transmissionof optical radiation in opposite directions through the switch and anyof the fibers.

The switch 10 is capable of selectively coupling each input fiber 11-18to any one of the output fibers 21-28, in a manner described in moredetail later. In fact, at any given point in time, the switch 10 iscapable of effecting an optical coupling between every one of the inputfibers 11-18 and a respective one of the output fibers 21-28. Thus, theswitch 10 implements a device of the type commonly known in the industryas an 8×8 optical cross connect (OXC) switch. However, it will berecognized that the present invention is not restricted to use in an 8×8switch, but could also be used in a switch having a larger or smallernumber of input fibers, and a larger or smaller number of output fibers.In fact, there are aspects of the present invention which also haveutility in devices other than an optical switch.

Turning now in more detail to the switch 10, it includes a housing 41which has a base plate 43 and a cap 44. The base plate 43 is made from aceramic glass composite which is plated with gold or silver, such as alow temperature co-fired ceramic (LTCC) available commercially as partnumber DuPont 951 from DuPont Electronic Materials of Research TrianglePark, N.C. This material has a coefficient of thermal expansion (CTE) of5.8 ppm/C°. The cap 44 is made from a metal material such as atungsten/nickel/copper alloy (WNiCu), with a CTE of 4.5 ppm/C°. The cap44 has four sidewalls arranged to define a square frame, and has a topwall extending between the upper ends of the sidewalls. The lower edgesof the sidewalls are soldered to the upper surface of the base plate 43using a suitable solder of a known type, such as gold/tin (AuSn) solder.

With reference to FIG. 2, the top wall of the cap 44 has a squareopening 51 extending vertically through it. A square window 52 is aplatelike element made from a borosilicate glass material, such as theglass material available commercially as catalog number 7059 fromCorning Incorporated of Danville, Va. The peripheral edges of the window52 are soldered to the cap 44 using a gold/geranium (AuGe) solder, andin particular are soldered to an annular surface portion which isprovided on the top wall and which extends around the opening 51. One ofthe sidewalls of the cap 44 has a rectangular opening 53 extendinghorizontally through it, and a different sidewall of the cap 44 hasanother rectangular opening 54 extending horizontally through it.

The housing 41 includes two lens section 56 and 57. The lens sections56-57 are briefly discussed here, and then are discussed in more detaillater. In the disclosed embodiment, they are each made from the sameborosilicate glass material as the window 52, which has a CTE of 4.6ppm/C°. The lens sections 56 and 57 could alternatively be made fromsome other suitable material, such as a fused silica material. The lenssections 56 and 57 each have on an inner side thereof an annular surfaceportion which extends along the peripheral edge thereof, and which issoldered to an annular surface portion that extends around an respectiveopening 53 or 54 on the exterior surface of the cap 44. In the disclosedembodiment, the lens sections 56 and 57 are each soldered to the cap 44using a gold/geranium (AuGe) solder. This provides a good hermetic sealbetween the lens sections and the cap, with good reliability.

Although the lens sections 56-57 are secured in place with solder in thedisclosed embodiment, they could alternatively be fused or bonded to thecap 44 in some other manner. As one example, the cap 44 could be madefrom steel, such the specific type readily commercially available from anumber of vendors as ASTM-F15. The lens arrays 56-57 could each be sizedto fit snugly within the associated rectangular opening 53 or 54, andthen the glass material of each lens array could be directly bonded tothe metal material of the cap using a known technique which produces abond commonly known in the art as a Frit seal. This provides a goodhermetic seal between each lens section and the cap, which is reliableeven in harsh environments.

Another example of an alternative technique for bonding the lens arrays56-57 to the cap 44 is to use, instead of a solder, an epoxy adhesive ofa type known in the art. This represents a low temperature sealingtechnique, which is suitable for some applications and provides goodresistance to moisture.

The housing 41 thus includes the base plate 43, cap 44, window 52, andlens sections 56-57. The housing 41 is a hermetically sealed container,the interior of which is subject to a vacuum. As evident from theforegoing discussion, the various parts of the housing 41 are made frommaterials having similar coefficients of thermal expansion, so thattemperature variations will not generate stresses which tend to breakthe solder connections and/or effect an increase in insertion losses.The input fibers 11-18 each have an end which is fused to an outer sideof the lens section 56, and the output fibers 21-28 each have an endwhich is fused to an outer side of the lens section 57, as discussed inmore detail later.

With reference to FIG. 2, a spacer plate 61 is mounted on the topsurface of the base plate 43, within the interior of the housing 41. Inthe disclosed embodiment, the spacer plate 61 is made from alumina, andhas an exterior surface which is plated with copper. The spacer plate 61has a CTE in the range of about 6.9 to 7.3 ppm/C°. A digital micromirror device (DMD) 71 of a known type is mounted on top of the spacerplate 61, the spacer plate 61 serving to establish an appropriatevertical position for the DMD within the housing 71. A DMD of the typeshown at 71 is also sometimes referred to in the art as amicro-electro-mechanical systems (MEMS) device. In the disclosedembodiment, the DMD 71 is an existing component manufactured by AnalogDevices, Inc. of Norwood, Mass. The DMD 71 is soldered to the spacerplate 61, using Indalloy 164 solder, which is well known in the art.

The DMD 71 includes a platelike silicon substrate 73, and has 64 mirrorparts movably supported on the upper side of the substrate 73, eight ofthe mirror parts being designated by reference numerals 81-88 in FIG. 1.The 64 mirror parts of the DMD 71 are arranged in a two-dimensional 8×8array, with eight rows and eight columns. Each of the mirror parts canpivot about an axis adjacent one edge thereof between an approximatelyhorizontal position generally flush with the top surface of thesubstrate 73, and an upright position extending vertically upwardly fromthe substrate 73 approximately perpendicular thereto. Each mirror partthus pivots through an angle of approximately 90°. As evident from FIG.1, the eight mirror parts identified by the reference numerals 81-88 areeach shown in the upright position, and all of the other mirror partsare shown in the horizontal position.

In the DMD 71, movement of each mirror part is effectedelectromagnetically. However, it would alternatively be possible to moveeach mirror part in some other manner, for example using electrostaticforces. Each of the mirror parts has on one side thereof a reflectivesurface, the reflective surface being on the top side of the mirror partwhen the mirror part is in its horizontal position. When the mirror partis in its upright position, the reflective surface forms an angle ofsubstantially 45° with respect to one of the input fibers 11-18 and alsowith respect to one of the output fibers 21-28. For example, it will benoted that the reflective surface on mirror part 81 forms an angle of45° with respect to each of the fibers 11 and 24.

It will thus be recognized that each mirror part can optically coupleone of the input fibers to a respective one of the output fibers, forexample as indicated diagrammatically in FIG. 1 by an L-shaped linewhich represents an optical path extending from the input fiber 11 tothe mirror part 81 and then to the output fiber 24. When each mirrorpart is in its retracted or horizontal position, it is vertically lowerthan and does not interact with radiation traveling between any of theinput and output fibers. On the other hand, when each mirror part is inits upright position, it reflects radiation traveling between theassociated input and output fibers.

The movement of the mirror parts of the DMD 71 is controlled by digitalsignals received through a cable 93 that serves as a control interface.In the disclosed embodiment, the control interface 93 may conform to theindustry-standard RS-232 protocol, may be transistor-transistor-logic(TTL) signals, or may conform to some other interface protocol. Thedistal end of the control interface 93 is coupled to a suitable controlcircuit of a known type, which is not illustrated and described here indetail.

Turning in more detail to the lens sections 56 and 57, the lens sections56-57 in the disclosed embodiment are identical. Therefore, only thelens section 57 is described in detail. In this regard, FIG. 3 is adiagrammatic elevational view of the inner side of the lens section 57.As best seen in FIGS. 1 and 3, the lens section 57 includes a supportportion 106 which has the shape of approximately flat, rectangularplate. The lens section 57 also includes eight lens portions 111-118,which project outwardly from the inner side of the support portion 106,into the opening 54 through the wall of cap 44. Each of the lensportions 111-118 has approximately the shape of portion of a sphere, andserves as a collimating lens.

In the disclosed embodiment, the lens section 57 is made from a singlepiece of the above-mentioned Corning 7059 borosilicate glass material,the support portion 106 and the lens portions 111-118 being respectiveintegral portions of this single piece of glass material. The lenssection 57 can be fabricated in any suitable manner, for example bymolding the glass material, or by using a laser writing technique toselectively remove material from a larger initial piece of glass, untilthe remaining material defines the lens section 57. In the disclosedembodiment, the lens portions 111-118 are arranged at uniformly spacedlocations along a horizontal line, the center-to-center distance betweeneach adjacent pair of the lens portions 111-118 being equal to thedistance between two adjacent input fibers 11-18 or two adjacent outputfibers 21-28.

An approximately rectangular ring 126 of gold/geranium (AuGe) solder isprovided on the support portion 106, in particular on an annular surfaceportion thereon which extends around all of the lens portions 111-118.The solder ring 126 sealingly couples the lens section 57 to theexterior of the cap 44, and in particular to an annular surface portionthereon which extends around the opening 54 therein.

The manner in which the optical switch 10 is assembled will now bebriefly described. The spacer plate 61 and the cap 44 are each solderedto the base plate 43. The substrate 73 of the DMD 71 is soldered to thespacer plate 61. Next, the lens sections 56 and 57 are positioned withrespect to the housing 41, and then secured to the housing 41, in thefollowing manner.

The lens section 57 is placed in approximately the position shown inFIGS. 1 and 2. At this time, the output fibers 21-28 have not yet beensecured to the lens section 57. One of the mirror parts in the leftcolumn, for example the mirror part 86, is set to be in its uprightposition. A beam of radiation is caused to travel along the L-shapedpath associated with mirror part 86, so that it travels rightwardly inFIG. 1 to the mirror part 86, and then is reflected by the mirror partand travels downwardly.

While holding the lens section 57 stationary in a selected position withrespect to the housing 41, an end of an optical fiber is placed againstthe outer side of the lens section 57, and is moved relative to the lenssection 57 while measuring the amount of focused radiation from the lensportion 111 which enters the optical fiber. There are known techniquesfor moving the fiber and measuring the amount of radiation which entersit, one of which is described later. The maximum amount of radiationmeasured for this particular position of the lens section 57 isrecorded. In essence, this is a determination of the amount of radiationfrom the beam which, at the surface on the outer side of the lenssection 57, is focused by the lens portion 111 into a region ofpredetermined size around an optical axis of the convergent radiationtraveling away from the lens portion 111.

The left end of lens section 57 (FIG. 1) is then moved slightly, andheld stationary in this new position while the movement of the opticalfiber and the measurement of the radiation is repeated, in order toidentify and record the maximum measured amount of radiation associatedwith this new position of the lens section. This procedure is repeatedfor a number of additional positions of the lens section 57. Then, therecorded values are compared in order to select the position of the lens57 which is associated with the largest maximum measured amount ofradiation. The left end of the lens section 57 is then returned to thisselected position.

Next, a somewhat similar procedure is carried out for the lens portion118 at the right end of the lens section 57 in FIG. 1, using one of themirror parts located in the right column in FIG. 1, such as the mirrorpart 83. During this procedure, movement of the right end of lenssection 57 (FIG. 1) involves one-dimensional movement corresponding torotation of the lens section 57 about a central axis of the lens portion111. In particular, for each of several such positions of the right endof the lens section 57, an end of an optical fiber adjacent the outsideof the support portion 106 is moved relative to the lens section 57,while measuring the amount of focused radiation from the lens portion118 that enters the fiber when the lens section 57 is in that position.After this evaluation has been carried out for each of several differentpositions of the lens section 57, a determination is made of which ofthese positions of the right end of the lens section 57 yielded themaximum measured amount of radiation, and then the right end of the lenssection 57 is returned to this position.

With the right and left ends of the lens section 57 now held in theirempirically selected positions, the assembly is heated to a temperaturewhich melts the solder ring 126 (FIG. 3). The assembly is then cooled,so that the solder ring 126 hardens and causes the lens section 57 to befixedly and hermetically sealed to the cap 44 of the housing 41. Next,the lens section 56 is positioned and then secured to the cap 44 in amanner similar to that described above for the lens section 57.

Thereafter, each of the output fibers 21-28 needs to be aligned withrespect to the lens section 57, and then secured to the lens section 57.Similarly, each of the input fibers 11-18 needs to be aligned withrespect to the lens section 56, and then secured to the lens section 56.This is effected in the same manner for each of the fibers, and theappropriate technique is therefore described here for only one of thefibers, which is the output fiber 21.

In this regard, and with reference to FIG. 1, one of the mirror parts inthe left column of the 8×8 array is moved to its upright position, forexample the mirror part 86. Radiation is then directed along theL-shaped path associated with the mirror part 86, so that it travelsrightwardly in FIG. 1 to the mirror part 86, is reflected by the mirrorpart 86, and then travels downwardly to the lens portion 111, whichfocuses the radiation toward the surface on the outer side of thesupport portion 106 of the lens section 57.

FIG. 2 diagrammatically shows a fiber positioner 202 and a laser 203.There are commercially available devices which are suitable for use asthe fiber positioner 202, one example of which is a semi-automated fiberalignment system available under the trademark “ORION” from NewportCorporation of Irvine, Calif. There also are commercially availabledevices which are suitable for use as the laser 203, one example ofwhich is a laser available as model J48-1W from Synrad, Inc. ofMukilteo, Wash.

The fiber positioner 202 is operatively coupled to the output fiber 21,as indicated diagrammatically by a broken line 206. The fiber positioner202 can monitor the amount of radiation passing through the fiber 21 toits distal end, as indicated diagrammatically by a broken line at 207,while the fiber positioner 202 physically moves the proximal end of thefiber 21 adjacent the flat outer surface of the support portion 106 oflens section 57. This movement includes linear movement of the fiber endin two orthongal directions which are each parallel to the flat outersurface on support portion 106. Also, this movement may includevariation of the angle formed by the end of the fiber 21 with respect tothe outer surface of the support portion 106, in particular variation ofthis angle within a small range around a position in which the fiber endis perpendicular to the flat outer surface on support portion 106.

The fiber positioner 202 has the capability to position the fiber 21according to a selected criteria. In the disclosed embodiment, thecriteria is to move the fiber 21 to the position in which it receivesthe maximum amount of radiation from the lens portion 111, whichtypically means that the end of the fiber 21 would be positioned at thelocation where the flat outer surface of the support portion 106 isintersected by an optical axis along which the curved surface on thelens portion 111 is effectively focusing the beam of radiation.

When the fiber positioner 202 has positioned the fiber 21 so as tosatisfy this criteria, the fiber positioner 202 enables the laser 203,as indicated diagrammatically by a broken line 208. The laser 203 thendirects onto the very end of the fiber 21 a laser beam, which isindicated diagrammatically by a broken line 209. The laser beam 209 hasthe effect of melting the end of the fiber 21 and also the adjacentmaterial of the support portion 106, so as to fuse the end of fiber 21to the flat outer surface of the support portion 106, and therebyfixedly fasten them together. This forms a strong molecular bond betweensimilar or identical materials. In the disclosed embodiment, the fiberpositioner 202 and the laser 203 automatically carry out thispositioning and fusing of the end of the fiber 21 with respect to theflat outer surface of the support portion 106.

After the end of the fiber 21 has been oriented and fused in this mannerto the lens section 57, a small quantity of a known adhesive 216 mayoptionally be applied around the region where these parts have beenfused. After this adhesive sets, it adds mechanical strength to theconnection between the fiber 21 and lens section 57, and serves toresist relative movement between them that might weaken and/or sever thelaser-fused connection. The adhesive 216 does not affect the opticaloperation of the fiber 21 and the lens section 57.

Although the disclosed embodiment uses a laser beam to fuse each fiberto the associated lens section, with or without the subsequentapplication of an adhesive, there are alternative techniques which alsofall within the scope of the present invention. For example, onepossible alternative is to use an arc fusing technique instead of alaser beam, where two electrically conductive probes are placed onopposite sides of the fiber closely adjacent the lens section, and thena substantial voltage is applied across the probes in order to generatean electrical arc which fuses the fiber to the lens section. Afterfusing the fiber and lens together using this arc fusing technique, anadhesive can optionally be applied in the same manner as discussed abovefor the adhesive 216. Any other suitable alternative approach could alsobe used.

As evident from the foregoing discussion, the disclosed embodiment is atwo-dimensional optical switch 10, which effects switching between afirst group of optical fibers 11-18 and a second group of optical fibers21-28. However, it will be recognized that the invention is applicablein other contexts, including but not limited to a three-dimensionaloptical switch, an optical multiplexer, an optical demultiplexer, or anoptical add-drop multiplexer (OADM).

The present invention provides a number of technical advantages. Onesuch technical advantage is that several optical fibers, severalcollimating lenses and a window for a hermetic package are all combinedinto what is effectively a single integral component. This permits ahigh degree of alignment between the fibers, the collimating lens andoptical components within the housing, so as to achieve a degree ofaccuracy which can reduce insertion losses for input fibers to outputfibers by 50% or more over preexisting approaches. For example, thepresent invention can provide insertion losses less than 2 dB over thenormal operational temperature range for devices of this type. Further,this accuracy can be achieved more easily and reliably than inpre-existing approaches, thereby producing higher production yields.

Since the fibers, lenses and window are effectively a single commoncomponent with an effectively uniform coefficient of thermal expansion,alignment errors between these elements are virtually negligible overthe operational temperature range of the device, thereby avoiding theCTE alignment errors that tend to contribute to insertion losses inpre-existing configurations. The provision of these elements as a commoncomponent also helps to reduce or eliminate susceptibility to alignmenterrors caused by environmental factors such as vibration and/or shock.

Still another advantage is that each fiber and the associatedcollimating lens involve only a single exposed optical surface, which isthe curved surface on the lens portion, and this surface is disposedwithin the hermetically sealed housing, where it is protected fromenvironmental factors such as dust and moisture. Further, since the lenssection effectively integrates the collimating lenses into a window fora hermetically sealed housing, the parts count is reduced by avoidingthe provision of one or more separate transmissive windows in additionto a collimating lens structure, and this also avoids the inaccuraciesresulting from non-ideal characteristics of separate transmissivewindows, as well as the susceptibility of the external surfaces of thetransmissive windows to environmental problems such as dust andmoisture.

Although one embodiment has been illustrated and described in detail, itwill be understood that various substitutions and alterations are alsopossible without departing from the spirit and scope of the presentinvention, as defined by the following claims.

What is claimed is:
 1. An apparatus, comprising: a base; a plurality ofoptical parts supported on said base; a lens section which includes asupport portion made of an optically transmissive material, and aplurality of lens portions made of an optically transmissive materialand provided at spaced locations on a first side of said supportportion, said lens section being supported in a fixed relationship withrespect to said base so that said lens portions are each in alignmentwith a respective said optical part; and a plurality of optical fiberswhich each have an end secured to said support portion on a second sidethereof opposite from said first side, each said optical fiber havingsaid end thereof in alignment with a respective one of said lensportions; wherein each said optical fiber has said end thereof fused tosaid second side of said support portion of said lens section.
 2. Anapparatus according to claim 1, wherein each said lens portion is shapedto function as a collimating lens.
 3. An apparatus according to claim 1,wherein said support portion and said lens portions are respectiveintegral portions of a single piece of an optically transmissivematerial.
 4. An apparatus according to claim 3, wherein said supportportion has an approximately platelike shape; and wherein each said lensportion projects outwardly from said first side of said support portion,and has a shape which is approximately a portion of a sphere.
 5. Anapparatus according to claim 3, wherein said single piece of opticallytransmissive material is made from one of a borosilicate glass and afused silica material.
 6. An apparatus according to claim 1, including ahousing having a wall portion with an opening therethrough, said basebeing a portion of said housing, said optical parts being within saidhousing, and said lens section being a part of said housing which isdisposed externally of said wall portion with said lens portionsprojecting into said opening; wherein said support portion of said lenssection has on said first side thereof a first annular surface portionwhich extends around said lens portions; and wherein said wall portionhas on an outer side thereof a second annular surface portion whichextends around said opening and which is sealingly coupled to said firstannular surface portion.
 7. An apparatus according to claim 6, includinga solder ring disposed between said first and second annular surfaceportions for effecting said sealing coupling of said lens section tosaid wall portion.
 8. An apparatus according to claim 7, wherein saidhousing is hermetically sealed, said solder ring hermetically sealingsaid lens section to said wall portion.
 9. An apparatus, comprising: abase; a plurality of optical parts supported on said base; a lens sectonwhich includes a support portion made of an optically transmissivematerial, and a plurality of lens portions made of an opticallytransmissive material and provided at spaced locations on a first sideof said support portion, said lens section being supported in a fixedrelationship with respect to said base so that said lens portions areeach in alignment with a respective said optical part; and a pluralityof optical fibers which each have an end secured to said support portionon a second side thereof opposite from said first side, each saidoptical fiber having said end thereof in alignment with a respective oneof said lens portions; including a housing having a wall portion with anopening therethrough, said base being a portion of said housing, saidoptical parts being within said housing, and said lens section being apart of said housing which is disposed externally of said wall portionwith said lens portions projecting into said opening; wherein saidsupport portion of said lens section has on said first side thereof afirst annular surface portion which extends around said lens portions;wherein said wall portion has on an outer side thereof a second annularsurface portion which extends around said opening and which is sealinglycoupled to said first annular surface portion; and including a digitalmicromirror device which is disposed within said housing and whichincludes a plurality of movable mirror parts, each said optical partbeing a respective one of said mirror parts.
 10. An apparatus accordingto claim 9, wherein said housing has a further opening through a furtherwall portion thereof; including a further lens section which includes afurther support portion made of an optically transmissive material andincludes a plurality of further lens portions made of an opticallytransmissive material and provided at spaced locations on a first sideof said further support portion, said further lens section being aportion of said housing which is disposed externally of said furtherwall portion with said further lens portions projecting into saidfurther opening, said further support portion having on said first sidethereof a third annular surface portion which extends around saidfurther lens portions, and said further wall portion having on an outersurface thereof a fourth annular surface portion which extends aroundsaid further opening and which is sealingly coupled to said thirdannular surface portion; including a plurality of further optical fiberswhich each have one end secured to said further support portion on asecond side thereof opposite from said first side thereof; and whereinsaid mirror parts of said digital micromirror device are arranged in atwo-dimensional array having a plurality of rows and a plurality ofcolumns, each said lens portion of one of said lens sections beingaligned with a respective said row and each said lens portion of theother of said lens sections being aligned with a respective said column.11. An apparatus according to claim 9, wherein each said lens portion isshaped to function as a collimating lens.
 12. An apparatus according toclaim 9, wherein said support portion and said lens portions arerespective integral portions of a single piece of an opticallytransmissive material.
 13. An apparatus according to claim 12, whereinsaid support portion has an approximately platelike shape; and whereineach said lens portion projects outwardly from said first side of saidsupport portion, and has a shape which is approximately a portion of asphere.
 14. An apparatus according to claim 12, wherein said singlepiece of optically transmissive material is made from one of aborosilicate glass and a fused silica material.
 15. An apparatusaccording to claim 9, wherein each said optical fiber has said endthereof fused to said second side of said support portion of said lenssection.
 16. An apparatus according to claim 9, including a solder ringdisposed between said first and second annular surface portions foreffecting said sealing coupling of said lens section to said wallportion.
 17. An apparatus according to claim 16, wherein said housing ishermetically sealed, said solder ring hermetically sealing said lenssection to said wall portion.